Experimental work has been done to determine changes in the particle shape of portlandite grown in the presence of different ions. To quantify the experimentally observed changes in morphology a new analysis tool was developed, allowing the calculation of the relative surface energies of the crystal facets. The observed morphology in the presence of chlorides and nitrates was facetted particles of a similar shape, the addition of sulfates leads to hexagonal platelet morphology and the addition of silicates leads to the formation of large irregular aggregates. In addition to the experimental work, the surfaces of portlandite were studied with atomistic simulation techniques. The empirical force field used has first been validated. The equilibrium morphology of portlandite in vacuum and in water was then calculated. The results indicate that the presence of water stabilizes the [20.3] surface and changes the morphology. This is consistent with the experimental observation of [20.3] surfaces.

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The pursuit for complex geometries in contemporary architecture is driving innovation towards an unconstrained fabrication freedom for building components. Concrete is a building material with excellent structural and architectural qualities, which has the theoretical capacity of being cast into any shape. However, in practice, concrete is generally limited by the formwork manufacturing industry to simple, planar shapes. To overcome this fabrication limitation, this research investigates the use of large-scale 3D-printed plastic formworks for concrete components. This novel construction method takes advantage of the load-bearing capacity of concrete and relies on the fabrication-freedom inherited from the 3D printed formwork, thus making complex topologies and precise details possible for concrete structures. To demonstrate the potential applications of this method, skelETHon —a functional four-meter-long concrete canoe— was designed, built and raced in a regatta on the Rhine river. The research focused on the optimization of the 3D printing process for large-scale plastic formworks and on improving the stability of the thin formwork shells during casting.

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